Non-nutritive feed components have become a lightning rod topic over the past six to 12 months. A promising growing season in 2016 yielded less than desirable quality and some contaminants in many regions.

Goeser john
Director of Nutrition, Research & Innovation / Rock River Laboratory Inc.
John Goeser earned a Ph.D. in animal nutrition from the University of Wisconsin — Madison where h...

Environmental conditions, including drought and heavy rain, detracted from corn silage and grain crop quality through much of the Midwest and East. A muddy corn silage harvest, such as we experienced in the Midwest, and a droughty, dusty growing season in parts of the East harbors ash, a non-nutritive feed component.

Before getting into how ash contaminates feed, it’s important to understand what ash is and what level begins to suggest contamination.

When a forage testing lab determines ash content of a sample, the laboratory technician burns the sample down in an oven – much like wood in a wood stove. The only feed component left after the high heat burn is ash. Ash is comprised of soil (silica and other inorganic matter) contamination and mineral content, which do not burn.

Ash is not an entirely bad thing. The mineral contributions to ash are actually important to the animal’s health and performance. Nutritionists will typically carefully balance forage minerals, which should be measured with wet chemistry techniques, with supplemental vitamins and minerals in most dairy diets.


However, the non-mineral ash is useless to the animal and can work detrimentally – harboring soilborne, nutrition-robbing fungi and bacteria.

Source: Standing crops

Heavy rain, splashing soil onto forage crops and mudding through fields, is one way to bring additional ash content into forage. In many cases this is an unfortunate outcome from a challenging harvest season, such as 2016 in much of the Upper Midwest.

Drought conditions can also cause substantial ash contamination on a standing crop, due to blowing dust in the arid conditions. For example, several nutritionists in a drought stricken region recently questioned how ash contents could approach 12 or 13 percent of dry matter on scissor-clipped alfalfa and grass samples.

The forages were never laid down on the ground yet still exhibited greater than average ash concentrations. During discussion, we concluded that blowing dust contaminated the forage crop stand and the outcome was showing up on laboratory analysis results.

These conditions and outcomes are much more likely and common in the West., where the region has experienced drought for the past several years.

Source: Transportation at harvest

Ash contamination is equally likely to result from harvest techniques. During heavy rains and muddy environmental conditions, soil can bond onto tractor and trailer tires and into pack-tractor tire treads if the tractor must move off the bunker or pad. Consider how your forage gets to the silo. How much dirt or mud is tracked in during the process?

Ash can also become merged, raked or even sucked in with the large, fast and aggressive implements and equipment of today. Maximizing yield, in terms of cut height while picking up every last grass or alfalfa stem, can yield unintended outcomes.

Our industry also recognizes that lower cut heights and rakes, or mergers set too close to the ground, are picking up more than ideal soil amounts. Faster discbines can also create a vacuum-like condition where dust and soil are sucked into the forage windrow when moving at greater speeds. If your hay or haylage crop forage ash content value from a laboratory report is in the teens, ask yourself if you are harvesting too much ash.

Ramifications: Robbing nutrition

While recently troubleshooting herd health and performance issues, negative, soilborne bacteria (Clostridium spp.) were cultured and found related to gut health challenges, digestive upsets and performance losses.

The nutritionist in this case study was struggling to understand the source until we evaluated the corn silage and recognized that the corn silage ash content was 5 to 6 percent of dry matter in the bunker, year over year. Further, the corn silage demonstrated far less than ideal fermentation outcomes.

Despite a concrete base and walls, we discussed how the pack tractor needed to make turns and moves on the dirt when pushing chopped corn into the bunker.

This soil contamination was not only bringing pathogenic bacteria into the crop, which ultimately harmed the herd, but it also contributed to a less-than-stable forage. Mold, yeast and negative bacteria can be harbored in the soil, thus, contaminating with soil transports these microbial nutrition robbers into feedstuffs.

Ash also dilutes other positive nutrients in the forage, causing concern for hay and haylage crops more than corn silage. Rock River Laboratory will routinely recognize ash contents ranging from 13 to 20 percent of dry matter.

Think of this as 13 to 20 kilograms of non-nutritive soil in every 100 kilograms of forage. Yes, some of this 13 to 20 kilograms is mineral, but the goal for ash content should be less than 10 to 11 percent. So at 15 percent, there is likely 5 kilograms of unnecessary dirt within 100 kilograms of feed.

Our industry members can agree that we should be seeking to harvest quality corn silage, haylage and other feedstuffs, rather than depleting nutritive values with harvested ash. The best means to avoid this problem is through monitoring ash levels.

Then, use smart tactics to identify the contamination point to fix it, if high levels are found. You can monitor and assess ash content within your feedstuffs using a routine forage analysis – ash is almost always reported by your forage testing laboratory of choice.

If ash contents are greater than 4 percent for corn silage crops or greater than 10 to 11 percent in hay and haylage crops, ask yourself how the soil contamination happened. Bring in your harvest, agronomy and nutrition advisory team and strategize to fix the identified causes and work to find means to avoid future contamination in your harvest plan.

Diminishing ash contamination has the potential to improve animal performance, and could even save your equipment some extra work, making the fix well worth the cost of analysis.  end mark

PHOTO: Muddy harvest conditions experienced in the Upper Midwest this year can lead to higher ash content in feed and ultimately nutrition losses for cows. Photo provided by John Goeser.

John Goeser
  • John Goeser

  • Director of Nutrition, Research and Innovation
  • Rock River Laboratory Inc.
  • Email John Goeser